Motive-fluid engine



June 3, 1930.

J. T. MARSHALL MOTIVE FLUID ENGINE Filed May '7, 1926 9 Sheets-Shee't June 3, 1930 v J. T. MARSHALL MOTIVE FLUID ENGINE Filed May 7, 1926 9 Sheet-Sheet 2 June 3,1930. J. T. MARSHALL MOTIVE FLUID ENGINE Filed May '7, 1926 9 Sheets-Sheet 3 June 3, 1930. J. T. MARSHALL MOTIVE FLUID ENGINE Filed May '7, 1926 9 Sheets-Sheet June 3, 1930. J T. MARSHALL 7 1,760,952

MOTIVE FLUID ENGINE Filed May 7, 1926 9 Sheets-Sheet 5 June 3, 1930. J. T. MARSHALL MOTIVE FLUID ENGINE Filed May '7, 1926 9 Sheets-Sheet 6 June 3, 1930.

J. T. MARSHALL MOTIVE FLUID ENGINE Filed" May 7 1926 9 Sheets-Sheet Julie 3, 1930. MARSHALL. 1,760,952

MOTIVE FLUID ENGINE Filed May '7, 1926 9 Sheets-Sheet 8 June 3, 1930. J. T. MARSHALL MOTIVE FLUID ENGINE Filed May 7, 1926 9 sheets-sheet TO GOVERNOR 1 Theprineipal'objectofthe ini entionlisto Fig-. 'YAisa .15 steam so asto prevent Wife-drawing valve removedy' i Applicationfiled Mai i926, semi 107.41%, a d ii ireat 'iB ritaijn 159.11, i925, v

This invention relates to, motive'fiui d e11 Fig.' 5 is a part elevation'. andl'pait longls gines and'partieularly to those ofthe i efeiptudinal section illustrating'the engine cylin rocating type of constructiondesigned i501? def With-separate main steam admission, ere. reversing. It aims'to rovide im foyemefits 'pansionand exhanstvalyes; i

5 invsu'eh engines, hereinaftercalledfsteamen I Fig.l 6 is a gines, provide'dwith'j expansion- "vg-1 ves, V IVI of Fig." 5 V i wherein, such Valves a'feactuated directly Fig. .7 is. a View ofxthe right hand end of from Valve gear, for opeijatingithefniain the cylinder andassociatedg parts"shof "fin valves which control steam admission; --1 Fig. 5; i

I 7 part side 'elet ation. and pai"t I simplify the eonstinctin oftheq nginefvalvez section-of the ir'alvejshown intFig, but oni 1 st rv a debth S m f m opro d r m? a e l 11 1 7 full, qi ick adniission' ofsteainjtothejcylin- Fig. 7B is a plan 'vieWof"the,.-st1tiet e? ders, followediduly hyfaquiekfcutfoffof the shown in Fig. but ith.,.the. expansion 7 thereof and also to provide for separate e x- Fig. is a cross-section on the line haust'of the steam; l i -,line'VII-VII;qf Fig. 7B; j if r 'Another'object is tojpnovidefforsteamad F'g. .8 is ew similar-to Fig. .5 illustrat mission and exhaust for 'each c linder' inde ing a-eylindei' v provided'iwith n ain' stea1n v V pendently of eaehjother insueh manner: that j'and eixpansio n alves iofmodified fanny vfree exhaust can take. place independently of v Fig. 9..is a i'i V admission; eVen-Whenthe adrnission' is,out stfncti re of Figq'8*With1paitsremoved ofi during the earliest aart of the piston i partlyin sectlon and 1 1 1 stroke, so as toavoid settingj heavyhack ',-Fig. 1Q}diagrammaticallyillilstijates;"aj'i v p e sures.- u i gf j ws loss 0 p weriane om ifis fi f fi q l j e body -an K eliieiencyin enginesas' heretofore con'stiiiet cillatlng-llever'adaptingjthe Fengine 91 1186 I ed (particularly th'oseofthereYeifsingjtype)5i -r versing ne? owing chiefly to the prjesent'praetiee of ad; f The ahove definedfigui'es are di awn--to justing slottedlinksor slide hlocks' of appiir-.-"d1fierent scales and in some of thempa1 tenant valve'gear when the engine is running are oli'uttdto shoyvotherparts moreelearly. so. t hi h i v I 7 p '1. In thefexample ofreve slble. teamien me 'An engine embodyingvali g'iif CQOIdiDg lllustratedf 1n Figs. 1 vto/TC inclusive, tWo'" V g sion Valves andffrom the {expansion valves areshown'freeiprocable on flat seats Qand'Q .35"

Fig. 2 is a plan ifievs thereof '7 i on said r0d.- This 'junction-pieeemay beef 95.

. in Fig.3;

valves separate fromfthe mainlsteam'admise slid valve-form areempleyed: Th s wali s is illustrated in the appended drawingsto respectively, betweenslides 3 1witl1inasteam V which" reference will bemade infunthendeohest l SaidTVa V S p ly CQl Q l hfi scribing the inventionQ 4 Q admission of steam atfopposite lends l of'thei Insaiddrawings cylinderfi of theenginefihroiighports 6 and V Fig. 1-1 is'a side-elevation of an embodiment; 6? respectively. f I V r vof the invention with one form of valveigea They are shown i'connected togetherf'hy; a V for operating the main steam admission, exjunctic')n-pieee l an'd'with age-einmon vmei pension and exhaust valvesofIa'reversing 1 0d 'orspindle 7-, by a pin 8 cairiedonsaid i junction-pieceand eXtending-intoan eye 7* engine 5 Fig. 3 illustrates'a' general arrangement the skeletonyform shown in detail-Hill Figs. 1

of the valve gear as applied to the engine ocyl- 7A, 7B, and 70. 1' j inder of a locomotive; i The aforesaid rod 7 is mounted centrally.

Fig. 4 is a pai t'plali'o'f ths'ttfltllre ShQWIl" '11said 'juneti'on-piecefih ey -17. thefeof be-, I r. j 7

Qtoss5seetional ew o i.,.the 1i1ie 1 glit hand GIIaLYiGWFOf thgl i T eye 7 a and shouldenportions 7 of the shaft. 7 This recess isformed in a pendant-portion 1 of the junction-piece which carries a boss 1 extending upwardly into a'recess 7-? formed in the lower" surface of the'shaft enlargement for the eye 7 "2 The aforementionedpinfi is fixed to said pendant-portlon of the unction-piece as shown in Figs. 7A and 7C and the rod 7 is placed or dropped loosely in position on said pin. Theendsof this rod are adapted to pass through recesses 2 one of which. (shown in Fig. 7B) is forme'd in the upper surface of the aforementioned main valves 1 andl The ends of" said r'odalso pass through recesses formed in the undersurface of superposed expansion valves to bedecribed'hereinaften. 1

The main valves 1 and l are provided re- A .spe ctivel y with a number of steam inlet ports 9 communicatingwith achamber 10 formed inthevalvebodyand having a large outletport 11 arranged tocooperate with the corresponding steam inletport or 6* of the cyl lnder. V r c v The main steam admissionvalves. of an engine embodying this invention may be operated in various ways. In this instance they are operated by valve gear suitably-arranged g r in connection. with-a movable floating lever driven from the valve gear, as hereinafter described. The travel of these valves may beireverse'd'as in the case of an ordinary reversing engine, endwise movement of a blockworking in a slotted link pivoted for "drivin gby an eccentric orequivalent element associated with the crank shaft, such block belngconnected tothevalves through a radius, rod forming part of the valve gear for reversing the engine.

j I Mounted slidably on the main steam valves 1 and 1*, are flat faced expansion valves 14':

- and 14 respectively havinga number of longitudinally spaced ports l5 adapted to register with the steaminlet ports 9 of the first mentioned valves. ihese expansion valves are connected together by a sleeve 16 secured on a commonrod the arrangement being such as. to allow admission of a fullsupp'ly 10f steamalternatelyto each endof the cylinder 5 and to afterwards cut-off upon relatlvely small movement of the expansion valves. These expansion valves 14g421l1d 1 1 may be otherwise connected togetheigsucli as by elongate angle pleces 14 and 14 to prevent rocking of the valves. As indicated 7 in Fig. 7C, they are formed with recesses 1r through which the ends of the aforementionedrodor spindle 7 are extended.

These expanslon valves slldable on the main steam admission valves are in this instance provided with one or more actuated through afradius rod connected with a slide block in a slotted lever adapted to be oscillated by a floating lever pivoted to another block to which the main valve radius rod is also connected, the floating lever being adapted to oscillate through a link connecting therewith from the cross-head on the main'pistonrod as will hereinafter appear. The arrangement issuch that the combined oscillating movements of thefloating lever and the endwise movements of the latter slide block cause a quick admission and cut-ofl of the steam, thus allowing practically full boiler pressure to be admitted to the cylinder up to the point'of cut-off and thereby eliminating objectionable wire drawing of the steam. t v

In order to obtain the full advantage of the invention in an engine embodying valve gear suchjas herein set forth, the engine cylinder is provided with separate steam admission and exhaust ports controlled by separate valves, the exhaust valves being actuated by the valve gear so that movement of the main admissionvalves and of the expansion valves to vary the point of cut-off of steam admission will'have no prejudicial effect on the setting of the exhaust valves, which is such as to provide for' full and free exhaust of spent steam at the proper times.

It isusually advantageous to provide one or more main steam admission valves at each end of the engine cylinder so as toreduce steam portj clearance to a ininimum,and also desirable to provide one or more exhaust valves at each end of the cylinder. It is preferable to place these oppositely functioning valves on opposite sioe's of the cylinder. In the case of a horizontal engine, the main steam admission'valves are preferably arranged'on the top sides of the cylinders while the exhaust valves are preferably located on the lower sides thereof. The exhaust valves may be of flat slide or piston type and may be ports for fast running engines. V V In the illustrative construction, exhaust valves 18 and 18 in the form of fiat ported slides are shown controlling the passageof steam from exhaust outlets 19 and 19? located at opposite ends on the lower side of the engine cylinder. The steam is exhausted through ports 20 and 2O into pipes or chambers 21 and 21 which latter are connected to acommonexhaust or take-off pipe 21*. Said exhaust valves are connected together by means permitting adjustment thereof to relative positions. In this instance they are respectively provided with bosses22 and 22 extending into eyes or bridles 23 and 23* which latterconnect withrods 24L andQa respectively extending through stufiing boxes 25 and 25 The adjacent ends of these rods are oppositely threaded and engaged by a turnbuckle or coupling 26.

As thus I connected, the aforesaid exhaust valves are reciprocated by aslide :on 1 1'n e1-- 27 connected thrGnghlink'Q'Y I touthe shorter arm of a rockinglever28. Said lever ismounted on sleeve 28Flt0 oscillate on? a shaft 28 which latter is 'su pported in. bearings forming partof brackets 29 secured to the exhaust steam chest cover of the'cy-l nder (see! Figs. 3 and 7). In the case of-a locomotive as here represented,v this would be at the end of the cylinder nearest the smoke funnel into "which the aforementioned pipes 21' and 2l I exhaust. The longer arm 28 ofs'aid rockinglever is connected-to'andoscillated, by'a conpling rodBOextending from means herein- 7 after described by which the main-valvezrod 7 is reciprocated. I r I The aforesaid sleeve 28' on which the lever 28 isemounted may of course besupported by f anyother convenient part of the locomotive,

Inthi's instance the valve forop'erating the main'valv'es" 1 and 1 and the-ex;par'i-- sion valves 14and '14 comprises a curved slotted link or sector-platef31hereinafter."

called the mainlink which is supported in,-

term ediately-injtrlinnions'gl 'of brackets 31 the latter being fiXed to a solid-base" such as;

the spectacle plate 31 carrying oneend-oi the slid -b41332- for the'piston cross head 33- I lever arm 61 having?"connection" (as indiof'the locomotive; The main link 3 l maybe oscillated by'a rod 34 connected to its vlower "endand actuated froin a 'taiicrank (not. shown) fixed on the crank-pino1" a locomofive having outsid'e cylind is as in the exemplaryiconstrnction.

able .bioek'si toiw'hi'eh 'oneend of a radius v 41 to which ispi'voted the lower end ofj an oscillatingslottedlever 42, "which carries an rod 35 is'connected. Theotherendof said rod is connectedfat"35 to ya vertically disposed floating lever '36: whichfis pivoted atf 36 (near its upper end) to a'slide 'blo'ck 37,":

the latter being mounted in guides- 37 llfixed to the frontend of the steai'nlchest' '4 of the cylinder; To a lateral extension' 37 jof'said slide block, the main valverod 7 is connected; Thelower end of the aforesaidffloating,lever is-connected through a link 38to ajdepend ing extension- 33 of the" piston-cross-head 3'3, which.latteris-connected to the'piston 'rod v 390i theengine piston 40 (see-Fig. 5)l"" g On the opposite side ofithe aforesaid spec; made or transverse plate3I is fixed abra cliet endwise adjustableblock' 431 This last men tioned blo ck is pivotal-1y connected to a radius con-pling ro'd- 44 near one end thereof. {The other end of saidi-rod' is connec'tedfat 44? to Said main link carries anlendwi'se adjust-"- bearing-'46 may as'in'theexample shown he 'carriedbyya'bracket 47 (seeEigQ), which,

as inthe present instance may beboltedto the main frame-plate48 of a locomotive. The npperend of theo'scillating'lever 42 is connected by acoupling rod 49 to an upward extension 36? r the I aforesaid floating lever I above the p'ointo'f thelattefls connection with the slide-block 37, so that said oscillating vermav be :subje'ctfto" the" combined action of the fiocwlting lever 'and said slide block. l r

7 In order-to adj ust'theiposition -of the block I 43 iii the slotted os illating lever 42,"theafor-i I ,4 T said coupling-rod 44-is extendedbeyondits r point of connection'therewith and connected atitsend to the upper'end of a linkoO", the lower end of the latter being connectedto an arm 51 which intn'rnisconnected to abracket I v 51" secured to thet-ransverseplate;31F. "Said 7, 1

arm 51 is alsoconne'cted; through a-link52 to .a similar arm 53 which isfixed one horizontal shaft 54imounted in a bearing 55 at' thetop I of the aforesaid plate 31 and provided with .a' lever arm-' 56 having connection "f(Ias':indi: I I catedlwith arod for operation fi'om thel oco i inotivecabim either by handfor iautomati really as'preferre'd;

For purposesaof reversing thejengrine, the

radiusrodf (which connects with the'block 31 of the main-linli3l is intermediatcly connectedthrough alink 57 to a lever arm 58',

which latter i fi-X'ed-Qn a horizontal shaft 5 f' i monntedfin'abearingf60'at theupper'e'ndof the transverse plate 31 and provided with a cate'd) with a rod adapting it to operation or foot-lever in the usual way;

sionlvalves 14'and 14 I I I Extending laterally from the" aforesaid FigsB-imd- 9, themain steam admission valves within: theflocomotive fcabin either by hand V I -For forward 'rnnning of theengine, the r blocki 81 will-"be moved to one end of the slotted mainlink'and for backward running of the engine willbemovel to' 'the'opposite .endiof sai'dlinkswithout affecting the setting of "the oscillating lever 42' or {the block'f45 therein and-the indirectly connected expan are infthe form of piston'si63 and fly-arranged to reciprocate in fixed cylindrical liners 64 andz64;formedJrespectively'withanannnlar set. of ports 65 and 65 communicating with annularpassages-66 and66, while the 'latter communicates respectively with: the-steam I inletports 6 and 6? at 'the ends of the e gine cylinder; These I piston waives "ar Sh wn;

connected together by aslotted sleeve or jiincti'on-piece 67; are/also heldbetween' f l steam to annular sets'of steam ports-'Zland V end-plates 7 and 7 by the'valve-actuating rod 7, which in this instance extends there-' through and is provided with tightening nuts, 7

The expansion valves also are the form of pistons 69 and 69 arranged to, slide r,e.-

- spectively within the aforementioned main valves 63 and 63 spectiv ely with an annular set of steam ports 70 and 7.0 for controlling the passage of 71 in their associated main valves 63'and 63.

I The outer ends of the valves also control the passage of steam to-other annular'setsof steam ports 71 and 71-1n sa d main valves; These expansion valves are shown connected together by a sleeveorjunction-piece 72 in turn connected to the valve-actuating rod 17.

The separate exhaust valves 18- and 18 (one of which is shown in Fig. 9) areopere atedby surrounding'bridles 23 and 23 re- 'spectively connected thereto as represented iniFigs- 5 and 9. a

The wheels of thelocomotive to which the engine is applied are represented'at 77, 78 and 79, H r The operation of the engine equipped with V steam admission, expansion and exhaust valves with actuating gear of thenovel character' and arrangement hereinbefore described will doubtless be obvious to those skilled in the art or familiar with the operaits port 6 behind the pistoii40, causing the,

v latter to move outward (i. e. toward the left) and turn the crank shaft, thereby moving the valve operating. eccentric thereon (not shown) so as to rock the'main link and float, ing lever 36 to move the main valve spindle 7 to. the right. This motion continues until the eccentric having moved to an angular position corresponding to a dead center, ceases to rock the main link;

Movement thus imparted to the-valve 1 insuflicient (due toits lap, to fully uncover the portxfi and'admit steam'at the other end to'return the piston onits inward stroke, but on the pistons continued outward move ment, the floating lever, 36 (turning on its pivot 35 will cause the valve rod 7 (pivoted thereto at 36 to. quickly complete the valves travel to theright so as to fully uncover said port, the pivot 35 having previously come torestor nearly so. At the moment when the port 6 is thus quickly and fully opened to steam, thepiston will have nearly completed its stroke to the left and They are provided re- 1 the steam' previously therebehindwill have expanded and be ready for exhaust. At this samemoment, the exhaust ports are simultaneously open to exhaust by the rocking of the lever 28 (connected to the aforesaid fioatinglever at 86*), so that the spent steam may pass'to the atmosphere. 7

During the-described outward stroke of the piston, the upper end of the floating lever swings and moves the slotted link 42 (through rod 49.) so as to cause the expansion valve 14 to quickly overtake the main valve and cut off the steam thereto from thesteam chest 4 by bringing its openings 15' out of register with the ports 9 in said mainvalve. Upon moving the block 43 within the link 42, the stroke of the expansion valve may be varied as required. a

The described actions are of course reversely repeated on the backward or opposite stroke of the piston. As the piston completes its outward stroke the engine crank reaches dead center position and the eccentric 'meanwhile has moved to bring the main link into a position at which it is moving most rapidly to the right so as to keep the valve .1 open through the intervention of the rod and the floating lever, thus maintaining the position of the valve against the inward motion ofthe floatinglever by reason of its COIIIIEU- tion to the slide block 33 which, at this-time, is moving-toward the inner or right end of the cylinder. f

For reversal of the engine. the block 31 is simply moved to the upper end of the main link, in which position it opens and closes the valve 1 at the equivalent to the eccentrics displacement of180, while the block 43 of the expansion linkrequires no readjustment to adapt said link to the reversed travel of said-valve. i y

The foregoing description has reference to an engine of the reversing type as hereinbefore stated. For a nonereversing engine the aforementioned main link 31 with block 31 (Figs. 1, 2 and 3) may be omitted and replaced by a lever 7 5 pivoted at as represented in Fig. 10, wherein said lever is shown with one end connected to a rod 76 (correspondingwith rod 34) for oscillating the same from an eccentric or equivalent means associated with the crankshaft of the engine, and its other endconnected to the radius rod 35 which-connectswith the floating-lever 36 as hereinbefore described. In such an engine, the lever 56 for adjusting the point of steam cut-off would generallv be operated automatically by a governor.

By the use of steam admission and expane sion valves with actuating gear as herein described,-the engine may be operated in such mannerthat spent steam can exhaust freely from the cylinder, thereby eliminating the back-pressures which have heretofore so detrimentally affected the efficiency of recipro-.

in the latter between its connections with the,

main-admission valve rod and the aforesaid s lide block so as to oscillatesaid lever with saidlink member, means for moving said die block endwise in the link nember'for the pun. poseof reversing, a second slotted link piv oted: at oneend to said support'and having a rod connecting its other end to the upper endof said floating lever above its point of connection with said main valve rod, another die block movable endwise in said second slotted link, a rod-connecting said another die'block with the expansion valve rod and having. separate steam admission and exhaust means for adjusting the-position of. the last mentioned die block in its slotted link.

4. In a steam engine embodying a cylinder ports, separate main-admission and exhaust valves independently controlling the admis sionand exhaust ports, expansion valves cooperating with the main admission valves to control'the supply of steam through the.

admission ports, rods for separately reciprocating the main-admission. and expansion valves, a piston and a slide block reciprocated thereby, a valve operating gear comprising a floating lever having intermediate pivotal connection with the mam-admission valve rod and lowerendlink connection wlth said sl de block and an intermediately pivoted lever having rod connection at one end with said 'fioatinglever at its aforesaid point or connection with the main valve rod and aconnectlon at its other end with the exhaust from an eccentric on the engine crank-shaft,

a rod connecting said link member with saidfloating lever at a point in thelatter between, its connection withvtheslide block and the main-admission valve rod so as "to. oscillate said lever by said member, a slotted link pivoted at one end to the stationary; support and having a rod connecting its other'end to the upper end of the floating lever above its point of connection with said 1 main valve rod, a die-block adjustable endwise in said slotted link, means for adjusting said die-block in the slotted link and a rod connecting-said die-block with the expansion valve rod. it c 5. In a reversible steam engine embodying a cylinder having separate steam admission and exhaust ports, separate main-admissionand exhaust valves independentlycontrol ling the admission and exhaust. ports, expan-, sion valves co-operating with the main admission valves to control the supply ofsteam through the admission ports, rodsfor separately reciprocating the main admission and expansionvalves, a piston aslide block reciprocated thereby, a valveoperatmg gear comprising a floating lever pivotally conneoted intermediately to the main-admission valve rod and'having link connection at ts lower endiwith said slide block, an intermediately pivoted lever having rodconnec tion at one end withsaid floating lever at its aforesaid point of connection with the main valve rod and a connection at its other end with the exhaust valves for reciprocating the latter'simultaneously with the main admission valves, a stationary support, a slotted reversing link intermediately pivoted to said support and oscillated from an eccentric on the enginecrank shaft, a die block movable of connection with'the main-valve rod, an-, 7

other die block movable endwise in said second slotted link, a rod connecting said another die block with the expansion valve rod, and means for adjusting the position of the last mentioned die blockin its slotted link.

6. Avalve operating structure for a steam enginecomprising in combination with the engine cylinder, piston and cross-hea-d or slide-block zreciprocated thereby, a floating lever having a long arm rocking connection with said cross-head and an intermediate swivel connection with a member for reciprocating the main steam admission valves of the cylinder; a pivotally supported link oscillated from the crank shaft oi the engine and carrying a blockendwise movable thereon in an arc; a rod connecting said block with the floating lever at a point between the latters.,connectionswith said valve reciprocating .member and cross-head; means for shifting. said block endwise of said link from a remote point of engine control for changing the main valve movement andreversing the engine; 7 another link pivotally supported at one end, and having opposite end rod connection with the short arm of the floating lever beyond the latters aforesaid point of connection with the valve reciprocating member, said another link also carrying a block endwise movable thereon in an arc, a rod connecting the-block of said another link with the member reciprocating the expansion valves of the cylinder co-operatively with its main-admission valves, and means for shifting the last named block endwise of said another link from the aforesaid remote point of" engine control for varying the stroke extent of the expansion valves according to w'orkconditions of the engine.

7. A valve operating structure for a steam engine comprising in combination with the iii:

but in a dlI'ECtlOIl: opposite vto the'main adengine cylinder,-.piston and cross-head on 1 slide-blockfreciprocatedthereby, a floating lever having a long arm rocking COIlIlGCtlOIl with said cross-head and an'intermediate swivel connection'with a member for recip rocating the ma n steam admission valves of the cylinder and another swivel connection 7 at the same poin't with a rocking member 1mparting reciprocal movement to the exhaust valves of the cylinder simultaneously with mission valves; a pivotally supportedlink oscillated from thecrank shaft of the engine and carrying ablock endwise movable thereon in an arc; a rod connecting 'saidblock with the floating lever at a point betweenthelat V ters connections with said valve reciprocating member and cross-head; means for shift ingvsaid block endwise of said linkfrom a remote point'of engine controlfor, changing I the main'valve movement and reversingthe engine; another link pivotally supported at I one end and having opposite end rod connec tionwith the short arm of the floating lever beyond the latters aforesaid point of connection with the valve reciprocating mem ber, said-another link also carrying a block endwise movable thereon in an arc, a rod connecting the block of said another link i with the member reciprocating the expansion valves of the cylinder cooperatively'with its main-admission valves, and means for shift-i ing the last named block endwise of saidan other link from the aforesaid remote pointof enginecontrolforvarying the stroke ex- I tent of the expansion valves according to .work conditions of the engine. 3 I

8. A valve operating gear for a steam engine of the type embodying main steam admission and expansion valves, comprising a floating lever havinga long arm rockingconnection with the cross-head of the engine pis-' ton and an intermediate swivel connection with the member reciprocating Qthe main steam admission valves; a pivotally supported link oscillated from the crank shaft of the engine and carrying a block, movable endwise thereon in an arc; a. rod connecting; said block with the floating lever at a point between the latters connections with the valve reciproeating member s and cross-head, another link 'pivotally supported at one end and having opposite end rodconnection with the short arm of the floating lever beyond the latters aforesaid point of connection'with the valve reciprocating-member, said another link also carrying a'block movable endwise thereon in an arc and a rodconnecting the block of said another link with themember prising a floating lever having a long'arm,

rocking connection with the cross-head of the engine piston and an intermediate swivel connection with the member reciprocating the mainsteam admission valves; and anis other swivel connect on at the same pointv with a rocking member imparting reciprocal movement to the exhaust valves synchronously with the main-admission valves; a

,pivotally supported link oscillated from the floating lever beyond thelatters aforesaid point of connection with the valve recipro-.

eating member, said another link also carry- 7 inga block movableiendwisethereon in an are andja rod connectingthe block of said another link with the member reciprocating I I the expansion valvescooperatively with the a main-admission'valves.

10. In combination with a steam nginitf y the type embodying separate admissionand exhaust valves together with expansion valves co-operating "with the admission valves for controlling the steam admitted 1 therethrough from the steam chest, a valve operating structurei'including a floating l e ver-having longarm rocking connectionwith the cross-head ofthe enginepiston and an intermediate swivel connection :with the member reciprocating the admissionlvalves point with a, member imparting reciprocat1on to the exhaust valves synchronously with said admission valves, an oscillating link having swingingly adjustable rod connection I with the floating lever at a point between the t and another swivelflconnection at the same latters connections with the admission valve Y reciprocating member and the cross head and a rocking member having radius rod conf i r nection withthe short arm of the floating lever beyond the latters aforesaid point of Connection with the admission valvelrecip-- r rocating memberfand 1 a swingingly adj ustable connection also with the member reciprocating'the expansion valves whereby the 7 last mentioned valves overtake the admission valves during operation to eflect a quick cut off of steam therethrough. JAMES THOMPSON MARSHALL.

lreciprocatingthe expansion valves co-opera- ,tively with the main 3111111551011: valves.

9. A valve operating gear for a steam engine of the type "embodying separate steam admission and'exhaust valves andexpansion valves co-operatmg with the former, com-- no i 

